Well, the Fort Smith PPKs are brand new, only showed up on the market last year, so their market value is probably about $700 new and as low as $500 used, depending on condition.
The PPK has actually been produced by a number of manufacturers since it was first introduced. Walther has licensed out the rights six ways to sunday over the decades to Manurhin in France, Interarms, (who both imported Manurhin PPKs and had some manufactured domestically after the Gun Control Act of 1986) Smith & Wesson, and even FEG in Hungary who had previously manufactured a number of clones. Currently they're manufactured by Walther Arms USA in Fort Smith Arkansas.
Older models that were made in Germany or France will be worth more than American-made models of more recent manufacture. For example, I bought a like new Smith & Wesson PPK/S back in the Summer of 2016 for $500.
Basically, PPKs go like this in terms of value...
Pre-war Walther (Thurg) PPK > Wartime Walther PPK > Post-war Manurhin PPK > Walther (Ulm/Do) > Interarms/Ranger (Alabama) > Smith & Wesson PPK (Massachusetts/Maine) = Walther USA PPK (Arkansas).
In other words, yours is the newest and therefore the least desirable PPK.
That being said, don't sweat the market value or what the snobs have to say, the new Fort Smith PPKs are great little pistols with nicer fit/finish compared to the previous generation of PPKs which were manufacturered by Smith & Wesson under license, they just won't impress the elitists, the snobs, or collectors.